D/R Timing Chain Set ROCS6000D R Timing Chain SetSuit Holden 253 304 308 ROCS6000 CS6000 All Timing Chain Sets are made from billet steel, have 9 Keyways (unless otherwise stated) and have a heat treated crank sprocket. Red Series: standard billet steel set 9 Keyway Gold Series: premium billet steel set with all sprockets nitrided by better durability and longer life. 9 Keyway Blue Series: economy sets for quality but with a budget, Line Bore Kits available in . 002", . 005", .